Work has begun to remove a row of mature trees to make way for light rail construction at Centennial Park in Randwick in Sydney's east.

The work, which has seen crew members in cherry pickers trimming trees along the route, prompted a demonstration by locals and conservationists on Monday, calling for as many of the trees along Alison Road to be saved as possible.

The protesters said they feared a change in the light rail route after negotiations with the Randwick Council closed, had meant many more trees would need to be felled than originally thought.

They said many of the trees have irreplaceable heritage and environmental value, some being 100 years old.

Randwick Councillor Murray Matson, a member of The Greens, said he felt "dudded" by the change of route.

"It's very important that the re-alignment that the government put through after we signed that development agreement in good faith, be reversed," Councillor Matson said.

"We want an opportunity to sit down with the Government and put our proposals for a re-alignment to the middle of the road on the south side - that will save a whole line of trees along Centennial Park."

Jeff Angel from the Total Environment Centre said the light rail was a good initiative, but it should not come at a price that was not environmentally sound.

"We will be asking Transport New South Wales to grant us an inspection of the trees they intend destroying, and we intend to argue tree by tree which ones should be protected," Mr Angel said.

Claire Steigrad, who has lived in the area for 25 years, joined the protest with her husband Ian and son Harry.

"It's going to be scar not just on the eastern suburbs landscape, but the whole of Sydney," Ms Steigrad said.

"It impacts the whole of Sydney, it impacts air quality, it impacts green space, it impacts heat, it impacts wildlife."

Marg Prendergast, Sydney's coordinator general of CBD transport, said minimising the construction impact on the road network and ensuring as few trees as possible were removed had been leading priorities on the light rail project and will continue to be so in the next three years.

"At least two trees will be planted for every small tree we remove, four for every medium sized tree, and eight for every significant tree," Ms Prendergast said.

"That means we will plant significantly more new trees than we remove."